Nanofibers and nanotubes of sodium titanates , consisting of negatively charged thin layers of TiO6 octahedra and sodium ions between the layers were found to be effective adsorbents that can be used directly to remove radioactive Cs+, Sr2+ and Ra2+ cations. The materials can capture the radioactive cations from water by exchanging sodium ions in the titanantes with radioactive cations. The adsorption of the cations with larger size or higher charges (with respect to sodium ion) eventually causes deformation of the thin layers, which permanently traps the toxic cations in the titanate structures, and the adsorbed toxic cations can be safely deposited. Ag2O nanocrystals can be bonded to the surface of the titanate nanostructures, they efficiently captured radioactive I- anions from aqueous solutions by forming AgI precipitate on the titanates. Another superior property of the nanofibers and nanotubes is they can be readily dispersed into and separated from a liquid.